What is "pit orchestra"

A pit orchestra is a type of orchestra that accompanies performers in musicals, operas, ballets and other shows involving music. The terms was also used for orchestras accompanying silent movies when more than a piano was used. In performances of operas and ballets, the pit orchestra is typically similar in size to a symphony orchestra, though it may contain smaller string and brass sections, depending upon the piece. Such orchestras may vary in size from approximately 30 musicians (early Baroque and Classical opera) to as many as 90-100 musicians (Wagnerian opera). However, because of financial, space, and volume concerns, the musical theatre pit orchestra in the 2000s is considerably smaller (at most 20-30 musicians, including not more than ten string players).